Vanadium catalysts and desulfurization of sulfur compound-containing gases therewith

ABSTRACT

The desulfurization of gaseous effluents containing contaminating amounts of objectionable sulfur compounds, typically via the Claus reaction and notably in the presence of oxygen, utilizing a support substrate, e.g., titanium dioxide, having an active catalytic phase deposited thereon, such active catalytic phase being constituted of an electroneutral solid solution having the average composition: A4+/-yV2+/-xO9 in which A is a metal other than vanadium, e.g., magnesium, calcium or zinc, 0&lt;/=x&lt;/=0.2 and 0&lt;/=y&lt;/=0.5.

This application is a divisional of application Ser. No. 07/899,912,filed Jun. 17, 1992, now U.S. Pat. No. 5,369,076.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to novel vanadium catalysts particularlywell suited for the desulfurization of gases containing sulfur compoundsand to a process for the preparation thereof. This invention alsorelates to a process for the treatment of gases, notably industrialgaseous effluents, containing objectionable sulfur compounds, toeliminate such sulfur compounds therefrom, especially via the Clausreaction, wherein the sulfur values are recovered in the presence ofsuch catalysts and, in particular, of oxygen.

2. Description of the Prior Art

In the conventional Claus process, to which the present invention is notlimited, sulfur is recovered from gases containing hydrogen sulfide intwo stages. In a first stage, the hydrogen sulfide is burned in thepresence of a regulated amount of air to convert a portion of the gasinto sulfur dioxide. Then, in a second stage, the gaseous mixtureobtained is conveyed into reactors in series containing a catalyst, overwhich the Claus reaction is carried out:

    2H.sub.2 S+SO.sub.2 →3/nS.sub.n +2H.sub.2 O

Numerous catalysts have been employed for this reaction. Thus, it haslong been known to use an alumina-based catalyst therefor, such asdescribed in French Patent No. 1,570,161. A mixture of titanium dioxideand alumina has also been described for such purpose (U.S. Pat. No.4,141,962).

For reactions of this type, it too is known to this art to use catalystswhich, other than alumina, contain vanadium oxide.

One of the disadvantages of the above catalysts is their instabilityrelative to oxygen. Thus, when the gaseous effluent to be treatedcontains minor amounts of oxygen, such catalysts may be relativelyrapidly deactivated, e.g., as a result of the sulfatation of their facesurfaces. Their catalytic activity can then be irreversibly diminished.

A catalyst containing titanium dioxide deposited onto silica, or acatalyst based on titanium dioxide incorporating, as additives therefor,alkaline earth metal sulfates (U.S. Pat. No. 4,485,189), can also beused for such purpose. However, these catalysts also exhibit a loweractivity during the treatment of oxygen-containing gases. Thus, it isimportant that the catalyst retain a satisfactory degree of activity inthe presence of oxygen, because the industrial gases to be treated oftencontain small quantities thereof.

SUMMARY OF THE INVENTION

Accordingly, a major object of the present invention is the provision ofnovel catalysts, particularly for the desulfurization of gases (e.g.,industrial gases) containing objectionable sulfur compounds, andcharacteristically having a high activity during the Claus reaction andsubstantially maintaining such activity during said Claus reaction inthe presence of oxygen, particularly in the event of the utilization ofshort contact times.

Another object of this invention is the provision of a process for theproduction of such catalysts.

This invention also features a catalyst for treating gases containingsulfur compounds via the Claus reaction, typically in the presence ofoxygen, as well as a process for the treatment of gases containingsulfur compounds, particularly via the Claus reaction, notably in thepresence of oxygen.

Briefly, the present invention features novel catalysts comprising asupport substrate and a supported active catalytic phase constituted bya solid solution having the average composition:

    A.sub.4±y V.sub.2±x O.sub.9

in which 0≦x≦0.2 and 0≦y≦0.5, with the proviso that x and y are suchthat the electroneutrality of A₄±y V₂±x O₉ is assured and A is ametallic element stabilizing the valency of the vanadium at +5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

More particularly according to the present invention, by"electroneutrality" is intended that the sum of the positive charges ofthe cations of element A and vanadium is equal to the sum of thenegative charges borne by the oxygen atom.

Consistent herewith, A is a metallic element preferably selected fromamong calcium, magnesium and zinc, and more preferably is magnesium.

Preferably, the catalysts according to the invention are substantiallyfree or devoid of the oxides of the element A, e.g., magnesium oxide,and vanadium pentoxide, the presence of which would reduce the activityof the subject catalysts, particularly during a Claus reaction in thepresence of oxygen.

Thus, if y is greater than 0.5 and/or x is greater than 0.2, the freeoxide of element A appears, e.g., free magnesium oxide, sulfates aredeposited on the catalyst surface and the activity of the catalystdecreases and/or free vanadyl pentoxide is generated, which reduces theproperties the catalyst.

In a preferred embodiment of the invention, the catalytically active,supported phase is a solid solution having the average composition A₄ V₂O₉ and more preferably having the composition Mg₄ V₂ O₉.

In general, the amount of supported phase (constituted by a solidsolution of average composition A₄±y V₂±x O₉) preferably ranges from 2%to 15% by weight based on the catalyst and the amount of supportpreferably ranges from 85% to 98% by weight, based on the catalyst.

The catalysts according to the present invention typically have a BETspecific surface ranging from 5 to 250 m² /g and a total pore volumeranging from 0.15 to 0.80 cm³ /g.

The support substrates comprising the catalysts according to theinvention are advantageously based on at least one oxide, particularlyselected from among aluminum oxide, titanium dioxide, zirconium oxide,cerium oxide and silica. Preferably, such supports comprise titaniumdioxide, zirconium oxide or silica.

Titanium dioxide is the preferred support according to the presentinvention, particularly as a result of the better performancecharacteristics of the catalysts produced therefrom.

The support substrates can contain at least one additive, particularlyan additive for enhancing the mechanical properties of the finalcatalyst. Exemplary such additives include aluminum oxide, aluminumhydroxide, aluminum sulfate, silica, aluminosilicates (particularly ofthe formulae Al₂ O₃.6SiO₂ or 6Al₂ O₃.SiO₂), clays and sulfates ofalkaline earth metals, such as barium, calcium, magnesium or strontiumsulfates.

Thus, the support substrates comprising the catalysts according to theinvention can contain 10% to about 100%, e.g., 10% to 99.5% by weight,of at least one oxide selected from among aluminum oxide, titaniumdioxide, zirconium oxide, cerium oxide and silica, and 0% to 90%, e.g.,0.5% to 90% by weight, of at least one additive selected from amongaluminum oxide, aluminum hydroxide, aluminum sulfate, silica,silicoaluminates, clays and sulfates of alkaline earth metals.

In another preferred embodiment of the invention, such additivecomprises an aluminum oxide.

The support then comprises, e.g., 70% to 90% by weight of titaniumdioxide and 10% to 30% by weight of an aluminum oxide.

In another preferred embodiment of the invention, such additivecomprises an alkaline earth metal sulfate and more particularly calciumsulfate.

The support then comprises, e.g., 80% to 99% and preferably 80% to 90%by weight of titanium dioxide and 1% to 20%, preferably 10% to 20% byweight of an alkaline earth metal sulfate.

The support substrates according to this invention typically have aspecific BET specific surface area ranging from 5 to 300 m² /g and atotal pore volume ranging from 0.15 and 0.30 cm³ /g.

The catalysts according to the invention can be produced by depositingan active catalyst phase onto a support.

The catalysts are for example, produced by a process essentiallyconsisting of impregnating appropriate support with a solution of a saltof the metallic element A and a vanadyl salt. The salts used aretypically thermally decomposable.

The process according to the invention preferably comprises thefollowing stages:

(1) impregnating the support with a solution of a soluble salt of themetallic element A and a soluble vanadyl salt;

(2) drying the impregnated support; and

(3) optionally, calcining the dried support.

It is envisaged to repeat the stages (1), (2) and, optionally, (3) inrespect of the same support after drying and optionally calcining it.

The solution of impregnation can also comprise a mixture of a solutionof a soluble salt of the metallic element A and a solution of a solublevanadyl salt, or a solution of one of the two salts into which the othersalt has been introduced.

The salt concentration of the impregnation solution is selected as afunction of the amount of solid solution to be deposited onto thesupport. The amount of absorbed impregnation solution is dependent onthe absorption capacity of the support used.

The salt of the metallic element A is typically a nitrate, an oxalate,an acetate or an ammonium salt of said element. Similarly, the vanadylsalt is generally a vanadate of ammonium, acetate, oxalate or nitrate.Preferably, such salts are nitrates.

The conditions of impregnation are otherwise conventional to this art.

Prior to the impregnation stage, it is possible to add the at least oneadditive, as indicated above, to the support. This can be carried out byany appropriate process and, in particular, by impregnating the supportwith a solution of a precursor of said additive.

Moreover, prior to the impregnation stage, the support, optionallycomprising an additive, is typically shaped and is optionally driedand/or calcined.

The shaping is conducted via any known procedure. Such shaping canproduce articles having a variety of different shapes, e.g., spherical,cylindrical, in the form of solid or hollow extrudates, particularlyhaving a cylindrical or polylobar profile, shaped articles in the formof pellets, beads, granules, rings, monoliths and more particularlyhoneycombs. Especially preferred shaped articles include solid or hollowextrudates and monoliths.

The support substrates according to the present invention can beprepared by any appropriate, known process. Thus, when the support istitanium dioxide, the latter can, in particular, be provided by aconventional process of sulfuric acidulation of ilmenite afterhydrolysis, filtration and optionally drying.

This invention also features the use of the. catalysts described abovefor the treatment of gases and, in particular, industrial gaseouseffluents, containing sulfur compounds, particularly hydrogen sulfideand sulfur dioxide, to eliminate such sulfur compounds therefrom via theClaus reaction, notably in the presence of oxygen, which may comprisesuch gases.

The present invention also features the treatment of gases, e.g.,industrial gaseous effluents, containing sulfur compounds, particularlyhydrogen sulfide and sulfur dioxide, to eliminate said sulfur compoundstherefrom, particularly via the Claus reaction, wherein the catalystsdescribed above are employed therefor. The Clause reaction can becarried out in the presence of oxygen, which can emanate from saidgases.

The oxygen content of the gases to be treated can be up to 5% by volume,ranging, e.g., from 0.5% to 4% by volume and preferably from 1.5% to3.5% by volume.

When the gases to be treated also contain organosulfur compounds, suchas CS₂ and/or COS, the catalysts are well suited to eliminate same viathe hydrolysis thereof.

The catalysts according to the invention can be analyzed by means of ⁵¹V nuclei NMR spectra.

In the event that A is magnesium and the support is titanium dioxide,the spectrum obtained differs clearly from that of vanadium pentoxidesupported by titanium dioxide and is characteristic of the productrepresented by the supported phase of a catalyst according to theinvention.

In order to further illustrate the present invention and the advantagesthereof, the following specific examples are given, it being understoodthat same are intended only as illustrative and in nowise limitative.

EXAMPLE 1 (According to the Invention)

(1) A calcium nitrate aqueous solution was added to a titanium dioxidesuspension obtained after the hydrolysis and filtration of a titanylsulfate solution prepared by the standard technique of sulfuricacidulation of ilmenite. This suspension contained sulfate ions in anamount such that the weight ratio SO₄ ²⁻ /TiO₂ was 0.08 and the weightratio Ca²⁺ /TiO₂ was 0.33.

The suspension was dried at 150° C. for one hour. The powder obtainedwas mixed with water for 2 hours. The resulting paste was extrudedthrough a spinneret to produce extrudates, which were then dried at 110°C. for one hour and calcined at 400° C. for one hour. The thus preparedextrudates constituted a support containing 86.4% by weight titaniumdioxide and 13.6% by weight calcium sulfate and had a specific BETsurface of 120 m² /g, a total pore volume of 0.36 cm³ /g and anabsorption capacity of 0.35 ml/g.

(2) 19.3 kg of the above extrudates were impregnated with 6.77 liters ofan aqueous solution containing a mixture of magnesium nitrate andvanadyl nitrate. This impregnation solution was prepared by dissolving2.06 kg of magnesium nitrate (Mg(NO₃)₂.6H₂ O) in 3.90 liters of a 25%vanadyl nitrate solution (VO(NO₃)₃), followed by the addition of wateruntil a volume of 6.77 liters was provided.

After impregnation, the extrudates were dried at ambient temperature for24 hours and then calcined at 350° C. for 4 hours.

The catalyst produced had a specific surface of 90 m² /g and a totalpore volume of 0.33 cm³ /g. Its supported active phase content was 3.4%by weight, said phase being constituted by a solid solution of averagecomposition Mg₄ V₂ O₉.

EXAMPLE 2 (According to the Invention)

The operating procedure of Example 1 was repeated, but a catalyst havinga supported active phase content of 2.0% by weight was produced, saidactive phase having the same composition as the catalyst of Example 1.

EXAMPLE 3 (According to the Invention)

The operating procedure of Example 1 was repeated, but a catalyst havinga supported active phase content of 15.0% by weight was produced, saidactive phase having the same composition as the catalyst of Example 1.

EXAMPLE 4 (According to the Invention)

19 kg of extrudates prepared upon completion of phase (1) of Example 1were impregnated with 6.67 liters of an aqueous solution containing amixture of magnesium nitrate and vanadyl nitrate. This impregnationsolution was prepared by dissolving 2.62 kg of magnesium nitrate(Mg(NO₃)₂.6H₂ O) in 6.30 liters of a 25% vanadyl nitrate aqueoussolution (VO(NO₃)₃), followed by the addition of water until a volume of6.67 liters was provided.

After impregnation, the extrudates were dried at ambient temperature for24 hours, followed by calcination at 350° C. for 4 hours.

The catalyst produced had a specific surface of 65 m² /g and a totalpore volume of 0.31 cm³ /g. Its supported active phase content was 5.0%by weight, said phase being constituted by a solid solution of averagecomposition Mg₃.5 V₂.2 O₉.

EXAMPLE 5 (According to the Invention)

19 kg of extrudates obtained upon completion of phase (1) of Example 1were impregnated with 6.67 liters of an aqueous solution containing amixture of magnesium nitrate and vanadyl nitrate. This impregnationsolution was prepared by dissolving 3.34 kg of magnesium nitrate(Mg(NO₃)₂.6H₂ O) in 5.07 liters of a 25% vanadyl nitrate aqueoussolution (VO(NO₃)₃), followed by the addition of water until a volume of6.67 liters was provided.

After impregnation, the extrudates were dried at ambient temperature for24 hours, followed by calcination at 350° C. for 4 hours.

The catalyst produced had a specific surface of 80 m² /g and a totalpore volume of 0.32 cm³ /g. Its supported active phase content was 5.0%by weight, said phase being constituted by a solid solution of averagecomposition Mg₄.5 V₁.8 O₉.

EXAMPLES 6 TO 14 (According to the Invention)

Catalysts according to the invention were produced from known supportshaving different compositions, each of the supports containing a certaintitanium dioxide proportion. These catalysts comprised a supportedactive phase constituted by a solid solution of average composition Mg₄V₂ O₉. The catalysts were produced according to the procedure of phase(2) of Example 1, but a catalyst having a supported active phase contentof 5.0% or 5.1% by weight was produced.

The composition of each of these catalysts is reported in Table 1.

EXAMPLE 15 (Comparative)

A prior art catalyst was prepared, containing titanium dioxide depositedonto silica. Its titanium dioxide and silica contents were,respectively, 15% and 85% by weight. Such catalyst can be prepared asdescribed in British Patent No. 2,143,225.

EXAMPLE 16 (Comparative)

Another prior art catalyst was prepared containing calcium sulfate andtitanium dioxide. Its calcium sulfate and titanium dioxide contentswere, respectively, 13% and 87% by weight. Such catalyst can be preparedas described in U.S. Pat. No. 4,485,189.

EXAMPLE 17

Test of Catalytic Activity:

The catalysts of Examples 1 to 16 were tested in the Claus reaction,employing a fixed bed reactor and at a temperature of 220° C. Into suchreactor was introduced a gaseous mixture containing, by volume, 3% H₂ S,1.6% SO₂, 30% H₂ O and 65.4% N₂.

The gaseous mixture contact time was 0.08 seconds. The hydrogen sulfidedegree of conversion was measured for the first 6 hours of operation.Then, to the initial reaction mixture were added varying amounts ofoxygen (1% and 3% by volume, based on the initial reaction mixturevolume) and the degree of hydrogen sulfide conversion was measured.

Analysis of the compositions of the initial gaseous mixture and themixture exiting the reactor was by gas chromatography (e.g., usingLXM-3MD and Gazochrom 2101 chromatographs). The results obtained arereported in Tables 1 and 2.

Displaying a very satisfactory activity for the Claus reaction, thecatalysts according to the invention had an activity well above that ofthe prior art catalysts for the Claus reaction in the presence ofoxygen.

EXAMPLE 18 (According to the Invention)

5 kg of extrudates produced according to phase (1) of Example 1 wereimpregnated with 1.55 liters of an aqueous solution containing a mixtureof zinc nitrate and vanadyl nitrate. This impregnation solution wasprepared by dissolving 0.567 kg of zinc nitrate (Zn(NO₃)₂.6H₂ O) in0.904 liter of a vanadyl nitrate aqueous solution (VO(NO₃)₃) having avanadium concentration of 68 g/liter. After impregnation, the extrudateswere dried at ambient temperature for 24 hours, followed by calcinationat 450° C. for 4 hours.

The supported active phase content of the catalyst produced was 5% byweight, said phase being constituted by a solid solution of averagecomposition Zn₃.5 V₂.2 O₉.

EXAMPLE 19 (According to the Invention)

The operating procedure of Example 4 was repeated, but using calciumnitrate (Ca(NO₃)₂.6H₂ O) instead of magnesium nitrate to produce acatalyst having a supported active phase content of 5% by weight, saidphase being constituted by a solid solution of average composition Ca₃.5V₂.2 O₉.

EXAMPLE 20 (According to the Invention)

The operating procedure of Example 4 was repeated, but using as thesupport zirconium oxide extrudates instead of the extrudates preparedaccording to the technique of phase (1) of Example 1. The supportedactive phase content was 5% by weight, said phase being constituted by asolid solution of average composition Mg₃.5 V₂.2 O₉.

EXAMPLE 21 (According to the Invention)

The operating procedure of Example 4 was repeated, but using as thesupport extrudates prepared solely from titanium dioxide. The supportedactive phase content of the catalyst produced was 5% by weight, saidphase being constituted by a solid solution with an average compositionMg₃.5 V₂.2 O₉.

EXAMPLE 22

Test of Catalytic Activity:

The catalysts of Examples 4, 16 and 18 to 21 were tested in the Clausreaction employing a transverse reactor and a temperature of 220° C.Into such reactor was introduced a gaseous mixture having the followingcomposition, by volume:

    H.sub.2 S: 2%

    SO.sub.2 : 1%

    H.sub.2 O: 30%

    N.sub.2 : 67%

The gaseous mixture contact time was 0.5 second. The degree of hydrogensulfide conversion was measured for 6 hours of operation.

To the initial reaction mixture were then added varying amounts ofoxygen (0.3% and 1% by volume, based on the volume of the initialreaction mixture) and the degree of hydrogen sulfide conversion wasmeasured.

The analysis of the compositions of the initial gaseous mixture and themixture exiting the reactor was by gas chromatography (e.g., usingLXM-3MD and Gazachrom 2101 chromatographs).

The results obtained are reported in Tables 3 and 4.

As in Example 17, the catalysts according to the invention having a verysatisfactory activity for the Claus reaction, displayed a higheractivity than that of the prior art catalysts for the Claus reaction inthe presence of oxygen.

                                      TABLE 1    __________________________________________________________________________    Catalyst                     Support    Supported phase         Additive                                   Degree of H.sub.2 S conversion (%)    Avenge      Content                     TiO.sub.2 content                            content                                   % by volume of O.sub.2    Example         composition                (wt. %)                     (wt. %)                            (wt. %)                                   0    1.0  3.0    __________________________________________________________________________    1    Mg.sub.4 V.sub.2 O.sub.9                3.4  86.4   CaSO.sub.4                                   73   70   60                            13.6    2    Mg.sub.4 V.sub.2 O.sub.9                2.0  86.4   CaSO.sub.4                                   73   71   60                            13.6    3    Mg.sub.4 V.sub.2 O.sub.9                15.0 86.4   CaSO.sub.4                                   76   78   78                            13.6    4    Mg.sub.3.5 V.sub.2.2 O.sub.9                5.0  86.4   CaSO.sub.4                                   76   78   78                            13.6    5    Mg.sub.4.5 V.sub.1.8 O.sub.9                5.0  86.4   CaSO.sub.4                                   76   80   80                            13.6    6    Mg.sub.4 V.sub.2 O.sub.9                5.0  10     Al.sub.2 O.sub.3                                   73   70   65                            90    7    Mg.sub.4 V.sub.2 O.sub.9                5.0  90     AlOOH  77   75   75                            10    8    Mg.sub.4 V.sub.2 O.sub.9                5.1  99.5   SiO.sub.2                                   77   75   75                            0.5    9    Mg.sub.4 V.sub.2 O.sub.9                5.1  90     bentonite                                   76   76   75                            10    10   Mg.sub.4 V.sub.2 O.sub.9                5.1  80     Al.sub.2 (SO.sub.4).sub.3                                   75   75   74                            20    11   Mg.sub.4 V.sub.2 O.sub.9                5.1  80     Al.sub.2 O.sub.3.6SiO.sub.2                                   74   70   65                            20    12   Mg.sub.4 V.sub.2 O.sub.9                5.1  80     6Al.sub.2 O.sub.3.SiO.sub.2                                   75   70   69                            20    13   Mg.sub.4 V.sub.2 O.sub.9                5.1  80     BaSO.sub.4                                   75   71   65                            20    14   Mg.sub.4 V.sub.2 O.sub.9                5.1  15     SiO.sub.2                                   74   75   75                            83    __________________________________________________________________________

                  TABLE 2    ______________________________________    Catalyst        Degree of H.sub.2 S conversion (%)    Components      vol. % O.sub.2    Example content (wt. %)                        0         1.0    3.0    ______________________________________    15      TiO.sub.2                    SiO.sub.2                            73      60     39            15      85    16      TiO.sub.2                    CaSO.sub.4                            73      62     40            87      13    ______________________________________

                                      TABLE 3    __________________________________________________________________________    Catalyst                     Support    Supported phase         Additive                                 Degree of H.sub.2 S conversion (%)    Average     Content                     TiO.sub.2 content                            content                                 % by volume of O.sub.2    Example         composition                (wt. %)                     (wt. %)                            (wt. %)                                 0    0.3  1.0    __________________________________________________________________________     4   Mg.sub.3.5 V.sub.2.2 O.sub.9                5.0  86.4   CaSO.sub.4                                 71   74   90                            13.6    18   Zn.sub.3.5 V.sub.2.2 O.sub.9                5.0  86.4   CaSO.sub.4                                 69   74   90                            13.6    19   Ca.sub.3.5 V.sub.2.2 O.sub.9                5.0  86.4   CaSO.sub.4                                 68   73   80                            13.6    20   Mg.sub.3.5 V.sub.2.2 O.sub.9                5.0  0       0   65   70   80                     ZrO.sub.2 = 100    21   Mg.sub.3.5 V.sub.2.2 O.sub.9                5.0  100     0   71   75   88    __________________________________________________________________________

                  TABLE 4    ______________________________________    Catalyst        Degree of H.sub.2 S conversion (%)    Components      vol. % O.sub.2    Example content (wt. %)                        0         0.3    1.0    ______________________________________    16      TiO.sub.2                    CaSO.sub.4                            68      63     58            87      13    ______________________________________

While the invention has been described in terms of various preferredembodiments, the skilled artisan will appreciate that variousmodifications, substitutions, omissions, and changes may be made withoutdeparting from the spirit thereof. Accordingly, it is intended that thescope of the present invention be limited solely by the scope of thefollowing claims, including equivalents thereof.

What is claimed is:
 1. In a process for the catalytic desulfurization ofa gaseous feedstream containing contaminating amounts of at least onesulfur compound, the improvement which comprises, desulfurizing thefeedstream employing a catalyst having an active catalytic phasedeposited on a support substrate, said active catalytic phase comprisingan electroneutral solid solution having an average composition:

    A.sub.4±y V.sub.2±x O.sub.9

in which A is a metal other than vanadium, 0≦x ≦0.2 and 0≦y≦0.5.
 2. Thecatalytic desulfurization process as defined by claim 1, wherein said atleast one contaminating sulfur compound is selected from the groupconsisting of hydrogen sulfide, sulfur dioxide or mixture thereof. 3.The catalytic desulfurization process as defined by claim 2, wherein thedesulfurization process comprises a Claus reaction.
 4. The catalyticdesulfurization process as defined by claim 3, comprising conductingsaid Claus reaction in the presence of oxygen.
 5. The catalyticdesulfurization process as defined by claim 4, wherein said gaseousfeedstream comprises said oxygen.
 6. The catalytic desulfurizationprocess as defined by claim 5, wherein said gaseous feedstream comprisesan industrial gaseous effluent.